Preconceptional sex selection: past, present, and future

X-Y sperm selection: fact or fiction?

Selecting the gender of offspring has given rise to various and sometimes amusing stories. But regardless of which prefertilisation technique is used to influence the sex ratio of offspring it must fulfill certain criteria. First of all it must achieve a complete separation of the X and Y bearing sperm in sufficient quantities. Secondly sperm must be viable after separation and capable of fertilising. Sex preselection methods can be divided into two general groups which either separate spermatozoa on the basis of subtle physical or kinetic features or those which rely on distinctive nuclear characteristics unique either to X or Y chromosome bearing sperm. These, in turn, can be divided into in vivo methods designed to produce optimal conditions for fertilisation by either the X or Y bearing sperm, or in vitro sperm separation methods designed to separate X or Y bearing sperm. According to all published data, the different separation techniques have been shown not to be very effective. Only sex selection of spermatozoa by chromatin differences (cell sorting by flow cytometry) has demonstrated a significant enrichment of the X bearing sperm.

Current status of flow cytometry in cell and molecular biology

This review summarizes recent developments in flow cytometry (FC). It gives an overview of techniques currently available, in terms of apparatus and sample handling, a guide to evaluating applications, an overview of dyes and staining methods, an introduction to internet resources, and a broad listing of classic references and reviews in various fields of interest, as well as some recent interesting articles.